Well that’s diff-erent, Is my LSD bad?
Sometimes things don’t go to plan. Like when your limited slip differential mysteriously goes out without warning.
This is what we discovered last week after it began making the characteristic clunk and chatter of an LSD on the way out.
I had the Jeep up on jack stands swapping to swap out the old rear control arms when I gave one wheel a spin. The other spun in the opposite direction. Not good, the clutch packs weren’t engaging.
The good news, my differential is fine. When a limited slip goes out it will behave just like an open differential. It’s not ideal for older rigs, but Jeep’s brake-lock traction control system actually means the mechanical limited slip is rarely necessary.
What’s a limited slip differential
A limited slip differential is a mechanical traction device that prevents the wheels from spinning at drastically different speeds. The LSD allows the wheels to travel at different speeds under normal conditions but can to redirect power to the wheel with most grip should one being to slip. LSDs are not lockers and a wheel needs to be slipping for it to engage.
Not knowing if there was something else going on with the diff and not wanting to cause more damage to Jeep, we were forced to postpone our T.W.A.T. overland trip until we’d had it inspected.
As much as I would have liked to ignore the problem and let traction control take care of things, it would have been irresponsible. It’s never okay put off maintenance, especially when you know something isn’t right.
How to check your LSD
The Youtuber ChrisFix made this video a few years ago on how to check whether or not your vehicle has a limited slip differential. While it’s a little older, it still holds true for most vehicles today.
A simple prognosis
After a few hours at the dealer, I got the green light from the tech at the dealership. His explanation didn’t sit right with me and I was left feeling like they hadn’t given my Jeep the attention it needed.
He said the limited slip was engaging but recommended changing out the diff oil and adding a little friction modifier to help the clutches catch a little earlier.
Since I’d just changed out the fluid last fall, I picked up some Trans-X Limited Slip Gear Oil Additive and added about four ounces to my rear pumpkin.
After adding it I jumped in the Jeep and ran over to the local Sam’s Club parking lot where I did a few backward circles to the amusement of many.
Back up on the stands and it didn’t seem like it had made much of a difference. I’ll give it few hundred miles to see if any of that changes.
The unfortunate truth
The fact is with over 80,000 miles on the Wrangler, the limited slip is probably toast. Just a few quick searches revealed that even with regular maintenance Jeep’s Trac-Lok limited slip is prone to failure after about 60,000 miles.
With any luck, adding a few ounces of friction modifier and doing 10-12 figure eights in the Sam’s Club parking lot will breathe some new life into the tired clutches.
Whether or not this really solves the problem or I’ll be replacing it with a more robust locking differential has yet to be seen. For my purposes, I’m confident I can get by with Jeep’s brake-lock traction control system. Afterall most Wrangler’s don’t come with the limited slip and its benefits off-road are still hotly contested.
However, this is further proof, that there is no replacement for good preventative maintenance.advertisement
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